The present invention relates to a stable solid preparation of thiol ester derivative that will be very useful as a drug. More particularly, the present invention pertains to a stable solid thiol ester derivative preparation which contains as active ingredients a thiol ester derivative of the formula [I]: ##STR1## (where R is hydrogen or an acyl group; A is a residue of glycine, sacrosine or .alpha.-D-amino acid, the .alpha.-carbonyl group of which forms a thiol ester linkage with the sulfur atom; n is an integer 0 or 1; and B is a hydroxyl group or an amino acid residue) or a salt thereof, a water-soluble wax which is solid at ordinary temperatures, and sodium carboxymethyl starch (CMS-Na) and/or a monovalent electrolyte. More specifically, the present invention relates to a stable solid thiol ester derivative preparation which contains as active ingredients a thiol ester derivative of the formula [I]: ##STR2## (where R is hydrogen, or an acyl group which is selected from the group consisting of an acetyl, butanecarbonyl, cyclopropanecarbonyl, cyclohexanecarbonyl and adamantanecarbonyl groups and which is linked to an .alpha.-amino group of an amino acid of A; A is a residue of glycine, sacrosine or .alpha.-D-amino acid, the .alpha.-carbonyl group of which forms a thiol ester linkage with the sulfur atom; n is an integer 0 or 1; and B is a hydroxyl group or an amino acid residue) or a salt thereof, a water-soluble wax which is solid at ordinary temperatures, or sodium carboxymethyl starch and/or a monovalent electrolyte.
Thiol ester derivatives represented by the formula [I] have an action suppressing angiotensin converting enzyme.
Thiol ester derivatives which are in a solid state are sensitive to moisture. Therefore, when formulated by an ordinary method, they are affected by water contained in an excipient and by adsorption of moisture in the air, causing decomposition or oxidation, and thus resulting in deterioration of their properties. In order to stabilize such unstable thiol ester derivatives, it is necessary to formulate preparations having water in excipients removed as much as possible and to put them in glass bottles or package them in metallic moistureproof materials. Alternatively, in the case of preparations formulated by an ordinary method, they must be protected by, for example, enclosing a desiccant in their packaging. In these practices, the dehumidification required in formulation and rises in the packaging cost both increase the financial burden on the manufacturer, and it is also troublesome for users to handle and use such preparations.